Unit 5: Sixth Grade

How big is space?  How big is space?  That is a question man has been asking since the beginning of time.  When your grandparents were in school, it was thought that the Universe was very small, perhaps only 5000 light years across. A light-year is a unit of distance. It is the distance that light can travel in one year ○ It is about 6 trillion miles

Millions, Billions and Trillions  One million is a thousand thousands.  One million is a 1 with six zeros after it, denoted by 1,000,000.  One million seconds is about 11 and a half days.  One million pennies stacked on top of each other would make a tower nearly a mile high.  If you earn $45,000 a year, it would take 22 years to amass a fortune of one million dollars.  One million ants would weigh a little over six pounds.  One million dollars divided evenly among the U.S. population would mean everyone in the United States would receive about one third of one cent.

Millions, Billions and Trillions  Next up is one billion:  One billion is a thousand millions.  One billion is a 1 with nine zeros after it, denoted by 1,000,000,000.  One billion seconds is about 31 and a half years.  One billion pennies stacked on top of each other would make a tower almost 870 miles high.  If you earn $45,000 a year, it would take 22,000 years to amass a fortune of one billion dollars.  One billion ants would weight over 3 tons - a little less than the weight of an elephant.  One billion dollars divided equally among the U.S. population would mean that everyone in the United States would receive about $3.33.

Millions, Billions and Trillions  After this is a trillion:  One trillion is a thousand billions, or equivalently a million millions.  It is a 1 with twelve zeros after it, denoted by 1,000,000,000,000.  One trillion seconds is over 31 thousand years.  One trillion pennies stacked on top of each other would make a tower about 870,000 miles high - the same distance obtained by going to the moon, back to earth, then to the moon again.  One trillion ants would weigh over 3000 tons.  One trillion dollars divided evenly among the U.S. population would mean that everyone in the United States would receive a little over $3000.

How Big is The Universe?  500 years ago it was thought that the Universe was only a little bit bigger than the Earth.  In modern times, with the power of technology, we are finally starting to grasp the immense size of the Universe, and it is much bigger than anyone could have ever imagined.  y.com/space_size.htm y.com/space_size.htm

Hierarchy of the Universe  Name  Street Address  City  State  Country  Planet(s)  Terrestrial /Inner Planets---Mercury, Venus, Earth, Mars  Gaseous/Outer Planets----Jupiter, Saturn, Uranus, Neptune, and Pluto the Dwarf  Solar System---planets, Sun, asteroid belt  Galaxy---The Milky Way  Universe

Unit 6: Sixth Grade

Galaxies  Large groups of stars, dust and gas are called galaxies. Nebulas= large clouds of dust and gas  Galaxies come in a variety of shapes and sizes.  The largest galaxies contain trillions of stars

Types of Galaxies  There are many types of galaxies.  Edwin Hubble, the man who first declared that the Milky Way is not the only galaxy in our universe classified galaxies, mostly by their shapes in the 1920’s  Galaxies are classified as: Spiral, Elliptical and Irregular

Spiral Galaxies  Spiral Galaxies have a bulge at the center, and spiral arms.  The arms are made of gas, dust and new stars. Contain many nebulae that are forming new stars  The Milky Way (our galaxy) is believed to be a spiral galaxy

Elliptical Galaxies  Elliptical galaxies have very bright centers and little dust and gas.  They have no “arms”  Made of mostly old stars  Look like massive blobs of stars

Irregular Galaxies  “Leftover” galaxies.  They are not spiral, nor are they elliptical galaxies.  They do not fit into any classification group.  Irregularly shaped

Formation of the Universe  To understand how the galaxies are moving, imagine a loaf of raisin bread before it is baked.  Inside, each raisin is a certain distance from another raisin.  Why happens as the dough warms and rises?

Raisin Bread and the Universe  As the dough warms and rises, it expands, and all of the raisins begin to move further apart.  No matter which raisin you observe, the other raisins are moving farther away from it!

Raisin Bread and the Universe  Scientists believe that our universe, like the rising dough, is expanding.  Think of the raisins as galaxies. As the universe expands, the galaxies move farther apart!

The Big Bang Theory  Leading scientific theory about the formation of the universe.  13.7 billion years ago, all contents of the universe were compressed under extreme pressure, temperature, and density in a tiny spot.  Then, the universe rapidly expanded after a tremendous explosion.  The explosion continues to cause the universe to expand.

A Forever Expanding Universe  As our galaxies move farther apart, they get older and stop forming stars.  Therefore, stars will age and die, and the universe will get cold and dark after many billions of years.  However, the universe will continue to expand forever